Vehicle braking support device and braking support control method

ABSTRACT

Provided is a vehicle braking support device. The braking support device includes: detection units for detecting a state around a host vehicle; a braking support control unit for executing braking support by a braking device according to the detected state; and a vehicle stop control unit for maintaining a stopped state of a host vehicle after the host vehicle is stopped by the braking support control unit, and for releasing the stopped state of the host vehicle after a predetermined period has elapsed. The vehicle stop control unit, in a case where by using the detected state it is determined that it is desirable to maintain the stopped state of the host vehicle beyond the predetermined period, the vehicle stop control unit does not release the stopped state of the host vehicle until an operation by a driver is detected.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 16/869,531, filed on May 7, 2020, which is a U.S.bypass application of International Application No. PCT/JP2018/036724,filed on Oct. 1, 2018, which designated the U.S. and claims priority toJapanese Patent Application No. 2017-215148, filed on Nov. 8, 2017, thecontents of which are incorporated herein by reference.

BACKGROUND Technical Field

The present disclosure relates to a vehicle braking support device and abraking support control method.

An obstacle avoidance technique for avoiding a collision with a targetobject such as another vehicle or an obstacle existing in front of thehost vehicle using a detection result from an object detector such as acamera or a radar has been put to practical use. The obstacle avoidancetechnique also includes a braking support technique for performingbraking support of a vehicle using a detection result.

SUMMARY

The technique according to the present disclosure may be achieved in thefollowing aspect.

One aspect of the present disclosure provides a vehicle braking supportdevice. A braking support device for a vehicle according to a firstaspect includes a braking support control unit for executing brakingsupport by a braking device; and a vehicle stop control unit formaintaining a stopped state of a host vehicle after the host vehicle isstopped by the braking support control unit and for releasing thestopped state of the host vehicle after a predetermined period haselapsed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an explanatory diagram illustrating a vehicle equipped with abraking support device according to a first embodiment;

FIG. 2 is a block diagram illustrating a functional configuration of acontrol device provided in the braking support device according to afirst embodiment;

FIG. 3 is a flowchart illustrating a processing flow of vehicle stopmaintenance control executed by the braking support device according toa first embodiment;

FIG. 4 is an explanatory diagram schematically illustrating an exampleof the position of the host vehicle when a vehicle stop control processis executed in a first embodiment;

FIG. 5 is a time chart illustrating the change over time of vehiclespeed, braking support, brake hold, and driver operation in a case whereit is determined that it is desirable to maintain the host vehicle in astopped state beyond a predetermined period of time in a firstembodiment; and

FIG. 6 is a time chart illustrating the change over time of vehiclespeed, braking support, and brake hold in a case where it is determinedthat it is not desirable to maintain the host vehicle in a stopped statebeyond a predetermined period of time in a first embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As a conventional example of a braking support technique, it isdisclosed that a braking support for stopping the host vehicle isexecuted when identifying a traffic signal color or a stop line, orbraking support for stopping the host vehicle is executed in a casewhere it is determined that collision with a target object isunavoidable by only deceleration. Stopping a host vehicle by brakingsupport is not the stopping of a vehicle based on the intention of thedriver, so there are cases in which the driver may not be operating thebrake pedal, and there is a possibility that when application of thebrake fluid pressure to the braking device is immediately released afterthe vehicle stops, the vehicle may start moving. Therefore, a techniquefor maintaining the application of brake fluid pressure to the brakingdevice for a predetermined period after the vehicle is stopped bybraking support; or in other words, a technique for maintaining thestopped state of the vehicle has been proposed.

However, depending on the environment of the road on which the hostvehicle is stopped, there are cases in which it may not always bedesirable to release the application of the brake fluid pressure to thebraking device after the elapse of a predetermined period, and there arealso cases in which it may be desirable to release the application ofthe brake fluid pressure to the braking device after the elapse of apredetermined time period.

Therefore, depending on the surrounding conditions of the host vehicle,it may be desirable to execute maintenance of the stopped state of thevehicle after the vehicle is stopped by braking support, or it may bedesirable to execute the release of maintenance of the stopped state.

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings.

A vehicle braking support device and a vehicle braking support controlmethod according to the present disclosure will be described below basedon some embodiments.

First Embodiment

As illustrated in FIG. 1 , a braking support device 10 according to afirst embodiment is used by being mounted in a vehicle 500. The brakingsupport device 10 may include at least a control device 100, and mayfurther include millimeter-wave radars 21, 21 s, a monocular camera 22,a yaw rate sensor 23, a wheel speed sensor 24, a steering angle sensor25, a door sensor 28, and a braking support actuator 30. The vehicle 500includes wheels 501, a braking device 502, a brake line 503, a steeringwheel 504, a windshield 510, and a front bumper 520. Note that of themillimeter wave radars 21, 21 s, the monocular camera 22, and a LIDAR(laser radar), the vehicle may include at least the monocular camera 22as a detecting unit for detecting a state around the host vehicle; andin this embodiment, the millimeter-wave radars 21, 21 s and themonocular camera 22 are provided as detecting units. In the presentembodiment, the surrounding state of the host vehicle is a stateincluding: a road environment such as an intersection, a traffic signal,a road sign, and a road shape; and a traveling state of another vehicle.

In the vehicle 500, a braking device 502 is provided for each wheel 501.Each braking device 502 achieves braking of each wheel 501 by a brakefluid pressure supplied via a brake line 503 in response to operation ofa brake pedal by the driver. The brake line 503 includes a brake pistonand a brake fluid line for generating a brake fluid pressure accordingto the operation of the brake pedal. In the present embodiment, thebraking support actuator 30 is provided on the brake line 503, and thehydraulic pressure control that is independent of the operation of thebrake pedal is possible, whereby the braking support is achieved. Notethat, instead of a brake fluid line, the brake line 503 may be a controlsignal line, and a configuration for operating an actuator provided ineach braking device 502, or brake-by-wire may be employed. The steeringwheel 504 is connected to the front wheels 501 via a steering mechanism505 including a steering rod.

As illustrated in FIG. 2 , the control device 100 includes a centralprocessing unit (CPU) 101, a memory 102, an input/output interface 103,and a bus 104. The CPU 101, the memory 102, and the input/outputinterface 103 are connected via a bus so that bidirectionalcommunication is possible. The memory 102 includes: a non-volatile, readonly memory, for example a ROM, for storing a braking support controlprogram P1 for executing braking support by the braking device 502, anda vehicle stop control program P2 for maintaining a stopped state of avehicle after the vehicle has been stopped by braking support; and amemory that is readable and writable by the CPU 101, for example, a RAM.The CPU 101 functions as a braking support control unit by expanding andexecuting the braking support control program P1 stored in the memory102 in a readable/writable memory, and functions as a vehicle stopcontrol unit by executing the vehicle stop control program P2. Note thatthe braking support control unit may include the braking supportactuator 30 that receives a control signal from the CPU 101 and appliesbrake fluid pressure to the brake line 503 for braking support. Inaddition, the braking support control unit may be classified into theCPU 101 as a control unit that executes the braking support controlprogram P1 for controlling execution of braking support and transmits acontrol signal to each actuator, and the braking support actuator 30 asa drive unit that drives the braking device 502 for braking support. Thevehicle stop control unit may include the braking support actuator 30 inaddition to the CPU 101, or may be classified into the CPU 101 as acontrol unit that executes a vehicle stop control program P2 formaintaining the stopped state of the vehicle and transmits a controlsignal to each actuator, and the braking support actuator 30 as a driveunit that drives the braking device 502. The CPU 101 may be a singleCPU, a plurality of CPUs for executing each program, or a multi-threadtype CPU capable of simultaneously executing a plurality of programs.

The input/output interface 103 is connected to the millimeter-waveradars 21, 21 s, the monocular camera 22, the yaw rate sensor 23, thewheel speed sensor 24, the steering angle sensor 25, the door sensor 28,and the braking support actuator 30 via respective control signal lines.Detection information is inputted from the millimeter-wave radars 21, 21s, the monocular camera 22, the yaw rate sensor 23, the wheel speedsensor 24, the steering angle sensor 25, and the door sensor 28, and acontrol signal indicating a braking level is outputted to the brakingsupport actuator 30.

The millimeter-wave radars 21, 21 s are sensors that detect thedistance, relative speed, and angle of a target object by emittingmillimeter waves and receiving reflected waves that are reflected by thetarget object. In the present embodiment, a millimeter-wave radar 21 isarranged at the center of the front bumper 520, and two millimeter-waveradars 21 s are arranged on both side surfaces of the front bumper 520,respectively. The detection signals that are outputted from themillimeter-wave radars 21, 21 s may be, for example, a signal includinga point or a series of points indicating one or more representativepositions of a target object on which the received wave has beenprocessed in the processing circuits included in the millimeter waveradars 21, 21 s, or may be a signal indicating an unprocessed receivedwave. In a case where an unprocessed received wave is used as thedetection signal, the control device 100 executes signal processing forspecifying the position and distance of the target object. Note thatLIDAR may be used instead of a millimeter-wave radar.

The monocular camera 22 is an image pickup device that includes oneimage pickup element such as a CCD or the like, and is a sensor thatreceives visible light and outputs external shape information of atarget object as image data that is the detection result. The image datathat is outputted from the monocular camera 22 includes a plurality offrame images that are continuous in a time series, and each frame imageis represented by pixel data. In the present embodiment, the monocularcamera 22 is arranged at the center of the upper part of the windshield510. The pixel data that is outputted from the monocular camera 22 ismonochrome pixel data or color pixel data. Note that a compound-eyestereo camera may be used instead of the monocular camera 22.

The yaw rate sensor 23 is a sensor that detects the turning anglevelocity of the vehicle 500. The yaw rate sensor 23 is arranged, forexample, at the center of the vehicle. The detection signal that isoutputted from the yaw rate sensor 23 is a voltage value that isproportional to the turning direction and the angular velocity.

The wheel speed sensor 24 is a sensor that detects the rotation speed ofa wheel 501, and one is provided for each wheel 501. The detectionsignal that is outputted from the wheel speed sensor 24 is a voltagevalue proportional to the wheel speed or a pulse wave indicating aninterval corresponding to the wheel speed. By using the detection signalfrom the wheel speed sensor 24, information such as the vehicle speed,traveling distance of the vehicle and the like may be obtained.

The steering angle sensor 25 is a torque sensor that detects the amountof torsion, or in other words, the steering torque generated in thesteering rod by steering of the steering wheel 504. In the presentembodiment, the steering angle sensor 25 is provided on a steering rodthat connects the steering wheel 504 and the steering mechanism. Thedetection signal that is outputted from the steering angle sensor 25 isa voltage value proportional to the amount of torsion.

The door sensor 28 is a sensor for detecting whether the doors of thevehicle 500, in particular, the door on the driver's side, is in aclosed state. In other words, the door sensor 28 is a sensor fordetecting whether a door is completely closed, including a state inwhich the door is half-closed.

The braking support actuator 30 is an actuator for achieving braking bythe braking device 502 irrespective of operation of the brake pedal bythe driver. A driver for controlling the operation of the actuator basedon a control signal from the CPU 101 is mounted on the braking supportactuator 30. In the present embodiment, the braking support actuator 30is provided in the brake line 503, and increases or decreases the brakefluid pressure in the brake line 503 according to a control signal fromthe control device 100. The braking support actuator 30 is formed, forexample, of a module that includes an electric motor and a brake fluidpressure piston that is driven by the electric motor. Alternatively, abraking control actuator already introduced as an anti-skid device or ananti-lock brake system may be used.

A vehicle stop control process executed by the braking support device 10according to the first embodiment will be described with reference toFIG. 3 to FIG. 6 . The CPU 101 executes the vehicle stop control programP2 whereby, the processing routine illustrated in FIG. 3 is repeatedlyexecuted during a specified time interval; for example, from the startto the stop of the vehicle control system, or from when the start switchis turned ON until the start switch is turned OFF. Alternatively,execution of the processing routine illustrated in FIG. 3 may be startedwith a stop caused by braking of the vehicle 500 as a trigger. This willbe described below by taking the situation illustrated in FIG. 4 as anexample.

When the vehicle control system is started, the CPU 101 starts executingthe braking support control program P1. In the present embodiment, thebraking support control program P1 may be executed for avoiding andreducing contact with and collision with other vehicles, or may beexecuted for observing traffic rules at the time of autonomous drivingaccording to the traveling state or traveling route of the host vehicle.The braking support control program P1, in a situation approaching anintersection IS as illustrated in FIG. 4 , for example, uses lightinginformation of a traffic signal SG detected via the monocular camera 22,and intersection markings ISM or stop line information (not illustrated)on the road to determine whether or not the host vehicle M0 a is aboutto enter the intersection IS; and in a case of a situation that requiresa stop using light information or stop line information, stops the hostvehicle M0 a by performing braking support. Alternatively, in a casewhere the presence of a crossing vehicle M2 that is crossing thedirection of travel of the host vehicle M0 a is detected by using thedetection results from the millimeter-wave radars 21, 21 s, the hostvehicle

M0 a is stopped by executing braking support before the host vehicle M0a enters the intersection IS. In other words, even in a case of anintersection where a traffic signal SG is not installed, or in a casewhere the traffic signal SG is not recognizable by the monocular camera22, it is possible to perform braking support when entering theintersection IS. Furthermore, depending on the attributes of an oncomingvehicle M1 facing the host vehicle M0 a, the CPU 101 also performsbraking support within the intersection IS in order to avoid a frontalcollision or an offset collision, and, for example, the host vehicle M0b stops within the intersection IS. In the present embodiment, theoncoming vehicle M1 means a traveling vehicle that faces the hostvehicles M0 a and M0 b. Attributes include, for example, the distancefrom the host vehicles M0 a, M0 b to the oncoming vehicle M1, therelative speed of the oncoming vehicle M1 with respect to the hostvehicles M0 a, M0 b, the direction of the oncoming vehicle M1, the laprate between the host vehicles M0 a, M0 b and the oncoming vehicle M1,and the estimated time to collision (TTC) before colliding with theoncoming vehicle M1. These attributes are calculated and acquired usingthe detection results detected by the monocular camera 22, and themillimeter-wave radars 21, 21 s. The CPU 101 also uses the image datafrom the monocular camera 22 to calculate and acquire, for example, theexternal dimensions of the oncoming vehicle M1 and the lateral positionof the oncoming vehicle M1 with respect to the host vehicles M0 a, M0 bas attributes. Note that the accuracy of determining the direction ofthe oncoming vehicle M1 and the lap rate between the host vehicles M0 a,M0 b and the oncoming vehicle M1 may be improved by executing a datafusion process using the detection results from the millimeter-waveradars 21, 21 s and the image data from the monocular camera 22. The laprate means a ratio of overlap in the width direction, or in other words,the horizontal direction of the host vehicles M0 a, M0 b and theoncoming vehicle M1. Note that in the following, when the position ofthe host vehicle is not distinguished, the code M0 is representativelyused.

When starting the vehicle stop control program P2, the CPU 101determines whether stopping of the host vehicle M0 is a stop by brakingsupport as described above (step S100). In a case where it is determinedthat stopping of the host vehicle M0 is not a stop by braking support(step S100: NO), the CPU 101 ends this processing routine. Even in acase where stopping is not by the braking support, for example, in acase where the host vehicle M0 is located on an uphill or downhill, thebraking state may be maintained for a certain period of time as one modeof driver support.

In a case where it is determined that stopping of the host vehicle M0 isa stop by braking support (step S100: YES), the CPU 101 executes stopmaintenance (step S102). In other words, independent of the operation ofthe brake pedal by the driver, the CPU 101 starts a process formaintaining the brake fluid pressure applied to the braking device 502via the braking support actuator 30 for a predetermined specifiedperiod. The CPU 101 determines whether the host vehicle M0 is in arecommended stop environment (step S104). The recommended stopenvironment means an environment in which it is desirable to maintainthe stopped state of the vehicle by continuing stop maintenance of thevehicle executed after a stop by braking support without releasing evenafter a predetermined period elapses. More specifically, for example,corresponds to an environment in which the host vehicle M0 has notentered the intersection IS or the host vehicle M0 has not entered aroad. In addition, this also corresponds to an environment in which thehost vehicle M0 is stopped after detecting a crossing vehicle M2, whereit is estimated that an intersection exists in front of the vehicle. Forexample, the recommended stop environment corresponds to an environmentsuch as illustrated in FIG. 4 in which the host vehicle M0 a stopped bythe braking support is located at a position before the intersection IS,for example, on a stop line or at a position further away from theintersection than the stop line. Alternatively, in a case of entering aroadway from off the roadway, for example, from a parking lot; therecommended stop environment corresponds to an environment in which thehost vehicle is stopped by braking support before entering the roadway.In addition, the recommended stop environment corresponds to anenvironment in which the door is opened without the side brake beingoperated or the position of the transmission being shifted to neutral orthe parking position after the vehicle is stopped by the brakingsupport. In this case, after a predetermined period elapses after thedriver gets out of the host vehicle, the vehicle starts moving withoutthe driver in the vehicle. On the other hand, an environment that doesnot correspond to the recommended stop environment corresponds, forexample, to an environment in which the host vehicle M0 b that isstopped by braking support in the intersection IS is located asillustrated in FIG. 4 . Alternatively, corresponds to an environment inwhich the host vehicle is stopped by braking support on a road on whichthere is no traffic signal SG; for example, a dedicated motorway or ahighway. It should be noted that not entering an intersection IS, justbefore an intersection, and just before entering a roadway meanpositions where the vehicle will not come in contact with or collidewith another vehicle traveling on a lane crossing the lane of the hostvehicle.

In a case where it is determined that the host vehicle M0 is in arecommended stop environment (step S104: YES), the CPU 101 sets a periodof co instead of the predetermined period a as the stop maintenancedetermination period Tmax (step S106). In an environment where it isdesirable to maintain the stopped state of the host vehicle describedabove, when the stopped state of the host vehicle by braking support isreleased according to time and not depending on the intention of thedriver, there is a possibility that the driver is not operating thebrake pedal. As a result, the host vehicle may start to move with therelease of the stopped state of the vehicle, and there is a risk thatthe vehicle will collide with another vehicle due to entering anintersection IS or due to entering into an intersecting road; and in acase where the door is opened, there is a possibility that the hostvehicle will start moving without the driver being in the vehicle.Therefore, in order not to execute a release of stop maintenance of thevehicle according to the passage of time, the stop maintenancedetermination period Tmax is set to ∞ (infinity). Note that a finitetime such as 10 min or 30 min may be set instead of ∞.

In a case where it is determined that the host vehicle M0 is not in arecommended stop environment (step 5104: NO), the CPU 101 sets apredetermined period a as the stop maintenance determination period Tmax(step S108). As the predetermined period α, for example, a period of 2sec to 5 sec may be set. In an environment that does not correspond tothe recommended stop environment described above, or in other words, inan environment in which it is not desirable to maintain the stoppedstate of the vehicle; in a case where the vehicle continues to bemaintained in the stopped state after the host vehicle is stopped bybraking support, there is a possibility, on the contrary, that therewill be contact or collision with another vehicle that is following orwith a crossing vehicle. Therefore, in order to execute a release ofstop maintenance of the vehicle due to the passage of time, apredetermined period in seconds is set as the stop maintenancedetermination period Tmax.

The CPU 101 determines whether a braking maintenance period BHT hasbecome equal to or longer than the set stop maintenance determinationperiod Tmax, or whether an operation by the driver has been detected(step S110). Here, the braking maintenance period BHT is an elapsed timefrom when the host vehicle is stopped by braking support. In the presentembodiment, when the vehicle speed detected by the speed sensor 24 is 0km/h, it is determined that the host vehicle is in a stopped state. In acase where it is determined that none of the conditions is satisfied,the CPU 101 waits (step S110: NO).

In a case where it is determined that any one of the conditions issatisfied (step S110: YES), the CPU 101 releases the stop maintenancestate (step S112), and ends this processing routine. Changes over timein vehicle speed V (km/h), braking support (ON/OFF), brake hold(ON/OFF), and driver operation (ON/OFF) of driver operation duringexecution of this processing flow will be described. As illustrated inFIG. 5 and FIG. 6 , when braking support is turned ON (T1), the vehiclespeed V starts to decrease with a slight delay, and when the vehiclespeed V=0 km/h, or in other words, when the host vehicle stops, brakingsupport is turned OFF (T2). At the same time as when the braking supportis turned OFF, a brake hold, or in other words, stop state maintenanceis turned ON (T2). As illustrated in FIG. 5 , in a case where it isdetermined that the host vehicle M0 exists in a recommended stopenvironment, or in other words, when the stop maintenance determinationperiod Tmax=∞, the brake hold after braking support is continued untilthe time DR when an operation by the driver is inputted. Operation by adriver includes, for example, stepping on an accelerator pedal, steppingon a brake pedal, and turning OFF a main switch for turning ON/OFFbraking support. On the other hand, as illustrated in FIG. 6 , in a casewhere it is determined that the host vehicle M0 is not in a recommendedstop environment, or in other words, when the stop maintenancedetermination period Tmax is set to Tmax=α, the brake hold after brakingsupport is released when the period a has elapsed (T3).

With the braking support device 10 and the braking support controlmethod according to the first embodiment described above, in a casewhere it is determined that it is desirable to maintain the vehicle in astopped state for more than a predetermined period after the vehicle isstopped by braking support according to the detected state of thesurroundings of the host vehicle, the stopped state of the host vehicleis not released after a predetermined period has elapsed, and thestopped state of the host vehicle is not released until operation by thedriver is detected. Therefore, it is possible to execute maintenance ofthe vehicle stop after the vehicle is stopped by braking supportaccording to the surrounding state of the host vehicle. In other words,in a state where there is a possibility of contact or collision withanother vehicle due to the movement of the host vehicle caused byreleasing the stopped state of the host vehicle after a predeterminedperiod has elapsed, the stopped state of the host vehicle is maintained,so contact or collision with another vehicle due to movement of the hostvehicle may be avoided or reduced.

With the braking support device 10 according to the first embodiment, ina case where it is determined that it is not desirable to maintain thehost vehicle in a stopped state beyond a predetermined period after thehost vehicle has been stopped by braking support in accordance to thedetected surrounding conditions of the host vehicle, the stopped stateof the host vehicle is released after a predetermined period haselapsed. Therefore, release of maintenance of the vehicle stop after thevehicle is stopped by braking support may be executed in accordance withthe state of the surroundings of the host vehicle. In other words, in astate where there is a possibility of contact or collision with anothervehicle due to maintaining the stopped state of the host vehicle after apredetermined period has elapsed, the stopped state of the host vehicleis released, so contact or collision with another vehicle due tomovement of the host vehicle may be avoided or reduced.

Modifications

(1) In the first embodiment described above, in a case where it isdetermined that it is desirable to maintain the host vehicle in astopped state beyond a predetermined period, the stopped state of thevehicle M0 a is released after waiting for an operation by the driver;however, the driver may be notified on an instrument panel or on ahead-up display that the stopped state is being maintained. In thiscase, it is possible to prompt the driver to pay attention to the factthat the host vehicle is being maintained in the stopped state due to ajudgment on the vehicle side. Moreover, in addition to thatnotification, the driver may also be notified that the stopped state ofthe host vehicle is being maintained until operation of the acceleratoror the brake is performed. In this case, the driver may be informed ofwhat kind of operation will release the stopped state of the hostvehicle.

(2) In the first embodiment, the attributes of the oncoming vehicles M1and M2 are determined using the detection signals or image data from themillimeter-wave radars 21, 21 s, the monocular camera 22, or LIDAR and astereo camera as the target object detecting unit. On the other hand,the attributes of the oncoming vehicles M1 and M2 may also be determinedusing data, for example, the steering angle, the accelerator opening,and the brake operation amount related to the behavior of other vehiclesacquired via an inter-vehicle communication system.

(3) In the first embodiment, a braking support control unit and avehicle stop control unit are achieved by software by the CPU 101executing a braking support control program P1 and a vehicle stopcontrol program P2; however, may also be achieved by hardware by apre-programmed integrated circuit or a discrete circuit.

As described above, the technique according to the present disclosurehas been described based on embodiments and the modifications; however,the embodiments of the present invention described above are intended tofacilitate understanding of the present disclosure, and do not limit thepresent disclosure. The technique according to present disclosure may bemodified and improved without departing from the spirit and scope of theclaims, and includes equivalents thereof. For example, in order to solveall or part of the problems described above, or in order to achieve allor part of the effects described above, the embodiments corresponding tothe technical features of each of the forms described in the Summary,and the technical features of the modifications may replaced or combinedas appropriate. Moreover, technical features may be appropriatelyomitted, unless described as being essential in the present description.For example, a vehicle braking support device according to the firstform described above is taken to be an Application Example 1.

APPLICATION EXAMPLE 2

The vehicle braking support device according to Application Example 1,wherein

in a case where the detected state indicates that the host vehicle hasnot entered an intersection, that the host vehicle has not entered aroad, or that a vehicle is crossing in front of the host vehicle isdetected, the vehicle stop control unit determines that it is desirableto maintain the stopped state of the host vehicle beyond thepredetermined period.

APPLICATION EXAMPLE 3

The vehicle braking support device according to Application Example 2,wherein

in a case where it is detected that a door of the host vehicle is open,the vehicle stop control unit further determines that it is desirable tomaintain the stopped state of the host vehicle beyond the predeterminedperiod.

APPLICATION EXAMPLE 4

The vehicle braking support device according to any one of ApplicationExamples 1 to 3, wherein in a case where the detected state indicatesthat the host vehicle is in the intersection or that the host vehicle ison the road where a traffic signal is not arranged, the vehicle stopcontrol unit does not determine that it is desirable to maintain thestopped state of the host vehicle beyond the predetermined period, andreleases the stopped state of the host vehicle after the predeterminedperiod has elapsed.

APPLICATION EXAMPLE 5

The vehicle braking support device according to any one of ApplicationExamples 1 to 4, further including detection units (21, 21 s, 22) fordetecting a state around the host vehicle.

CONCLUSION

In the foregoing embodiments, vehicle braking support and brakingsupport control method have been described.

According to the present disclosure, a first aspect provides a vehiclebraking support device. A braking support device for a vehicle accordingto a first aspect includes a braking support control unit for executingbraking support by a braking device according to a detected state ofsurroundings of a detected host vehicle; and a vehicle stop control unitfor maintaining a stopped state of a host vehicle after the host vehicleis stopped by the braking support control unit, and for releasing thestopped state of the host vehicle after a predetermined period haselapsed; wherein in a case where by using the detected state it isdetermined that it is desirable to maintain the stopped state of thehost vehicle beyond the predetermined period, the vehicle stop controlunit does not release the stopped state of the host vehicle until anoperation by a driver is detected.

With the vehicle braking support device according to the first aspect,it is possible to execute the maintenance of the vehicle stop or therelease of the maintenance after the vehicle is stopped by the brakingsupport according to the surrounding state of the host vehicle.

A second aspect provides a vehicle braking support control method. Thevehicle braking support control method according to the second aspectincludes steps of: detecting a state surroundings a host vehicle;executing braking support by a braking device according to the detectedstate; and in a case where, when maintaining a stopped state of a hostvehicle after the host vehicle is stopped by the braking support, andreleasing the stopped state of the host vehicle after a predeterminedperiod has elapsed, it is determined by using the detected state that itis desirable to maintain the stopped state of the host vehicle beyondthe predetermined period, not releasing the stopped state of the hostvehicle until an operation by a driver is detected.

With the vehicle braking support control method according to the secondaspect, it is possible to execute the maintenance of the vehicle stop orthe release of the maintenance after the vehicle is stopped by thebraking support according to the surrounding state of the host vehicle.Note that the technique according to the present disclosure may also beachieved as a vehicle braking support program or a computer-readablerecording medium that stores the program.

What is claimed is:
 1. A vehicle braking support device comprising: adetection unit that detects a state of surroundings of a host vehicle; abraking support control unit for executing braking support by a brakingdevice according to the detected state; a vehicle stop control unit formaintaining a stopped state of a host vehicle after the host vehicle isstopped by the braking support control unit, and for releasing thestopped state of the host vehicle after a predetermined period haselapsed, wherein in a case where, by using the detected state it isdetermined that it is desirable to maintain the stopped state of thehost vehicle beyond the predetermined period, the vehicle stop controlunit does not release the stopped state of the host vehicle; and anotification unit that notifies a driver on an instrument panel or on ahead-up display that the stopped state is being maintained.
 2. Thevehicle braking support device according to claim 1, wherein the vehiclestop control unit, in a case where the detected state indicates that thehost vehicle has not entered an intersection, that the host vehicle hasnot entered a road, or that a vehicle is crossing in front of the hostvehicle is detected, determines that it is desirable to maintain thestopped state of the host vehicle beyond the predetermined period. 3.The vehicle braking support device according to claim 2, wherein thevehicle stop control unit, in a case where it is detected that a door ofthe host vehicle is open, further determines that it is desirable tomaintain the stopped state of the host vehicle beyond the predeterminedperiod.
 4. The vehicle braking support device according to claim 1,wherein the notification unit notifies the driver that the stopped stateof the host vehicle is being maintained until operation of anaccelerator or a brake is performed by the driver.